A trocar assembly is a surgical instrument that is used to gain access to a body cavity. A trocar assembly generally comprises two major components, a trocar tube and an obturator. The trocar tube having the obturator inserted therethrough is directed through the skin to access a body cavity through the tube in which laparoscopic or arthroscopic surgery and endoscopic procedures are to be performed. In order to penetrate the skin, the distal end of the trocar tube is placed against the skin which has been cut with a scalpel. The obturator has a sharp point or cutting edge at its distal end. By applying pressure against the proximal end of the obturator, the sharp point is forced through the skin until it enters the body cavity. The trocar tube is inserted through the perforation made by the obturator and the obturator is withdrawn, leaving the trocar tube as an accessway to the body cavity. Examples of trocar assembly devices are disclosed in U.S. Pat. Nos. 4,535,773 and 5,066,288.
The proximal end portion of the trocar tube is typically adjoined by a housing that defines a chamber having an open distal end portion that communicates with the interior lumen defined by the trocar tube. An obturator and other elongate surgical instruments or tools axially extend into and are withdrawn from the trocar tube through the proximal end portion of the chamber. it is the present practice to provide the chamber with an outer sealing means, such as a sealing grommet or gasket, through which the obturator or other instruments extend. The sealing means seals against the outer surface of the inserted instruments and thereby prevents fluids from leaving or entering the body cavity through the trocar tube. Examples of sealing means are disclosed in commonly assigned copending U.S. Pat. Ser. No. 07/779,040, filed on Oct. 18, 1991, and U.S. Pat. Ser. No. 08/046,587, filed Apr. 12, 1993, entitled Improved Seal Members For Surgical Trocars, filed concurrently herewith, the disclosures of which applications are incorporated herein by reference.
In developing trocar assembly devices for use in connection with surgical instruments having broad ranges of outer diameters (e.g., 2-5 mm or 5-11 mm), it is required that the outer seal member have an opening that is very small relative to the outer diameter of the instruments in the upper end of the size range. The insertion of large diameter instruments having sharp edges, such a surgical clip appliers and the like, cause tearing of the seal member. Accordingly, there is a need for a trocar assembly that includes means to protect the outer seal during the insertion of such surgical instruments. It is further desirable that such a protector means assist in the centering of instruments directed therethrough and assist in the dilation of the opening in the seal member as the instruments pass therethrough. It is also desirable that the protector means reduce frictional drag as an instrument is inserted through the outer seal.
The reference to the axial movement of the instrument through the seal member is intended to include insertion and withdrawal of the instrument as well as relative in and out movement of the instrument.